Right Hand Rule - a question

[Nesti (Mark)]

Is there a particular reason why the Right Hand Rule exists...ie viewed from in front of a current flow, the field generated rotates counter-clockwise...why is it right over left, or, why wouldn't the field oscillate back and forth (left to right, back to left and so on).

[mithrandir (Andrew)]

Originally Posted by Nesti

Is there a particular reason why the Right Hand Rule exists...ie viewed from in front of a current flow, the field generated rotates counter-clockwise...why is it right over left, or, why wouldn't the field oscillate back and forth (left to right, back to left and so on).

It's a convention. Thumb points in the direction of current (conventionally positive to negative). Fingers in the direction of the field (conventionally north to south). Switching one of those conventions, but not both, would give you a left hand rule.

With DC the current direction doesn't change, so the magnetic one doesn't either.

If the wire is carrying AC the electric and magnetic fields reverse together, but I seem to recall 90 degrees out of phase.

[Jarvamundo (Alex)]

Correct, Alternating m-field comes from alternating current.

Re 90 phase? Where electric strength and magnetic strength are always perpendicular, and always meet at zero. ie. where there is current there is always magnetism, vicer versa, see Maxwell's Laws.

Also important to think of the magnetic field as a fog (vector field). NOT lines (lines are just an easy way to quickly draw a field, like topographical lines to a mountain/valley.... they don't physically exist).

[gary]

Originally Posted by Nesti

Is there a particular reason why the Right Hand Rule exists...

If the question were "why does a magnetic field obey the right-hand rule,
rather than a left-hand rule, when a current flows through a conductor?", then as
the previous two respondents have noted it is a convention and because
most Electrical Engineers, including the one that formulated the right-hand
convention in the first place, are right-handed. (Though I personally know some
who are left-handed and still managed to graduate).

In other words, there is nothing "magical" about the handiness.

The relationship between an electric current and a magnetic field (i.e.
electromagnetism) was originally put forward by Ampère but it took Maxwell to
formulate in terms of field equations.

[Jarvamundo (Alex)]

heheh.. and Flemings right hand?

"the direction of the magnetic field (counterclockwise instead of clockwise when viewed from the tip of the thumb) is a result of this convention and not an underlying physical phenomenon." from wiki

(the hand of god could still be left)

[Nesti (Mark)]

Hang-on-hang-on, I'm still unsure as to why nature's disposition ("convention") on electromagnetism didn't go the opposite way, and that science's understanding didn't produce a left hand rule instead of the right hand rule.

I understand that theory is governed by observation, and theory tries to explain trusted tendencies (laws), but what if 150 years ago the observation were the opposite; what if a current produced a clockwise rotation if viewed from downstream (a left hand rule)? Conversely the current left hand rule would simply be replaced by the right for those applications they pertain.

My question really is, why is there a lopsidedness? Get what I mean, or am I missing something obvious here?

Further, I would completely understand if the old idea of an Ether Wind existed, then - as with Coriolis Effect - there would be a simple answer...a left hand effect or a right hand effect could be attributable to the angle a field was relative to an ether wind, but the ether wind [apparently] does not exist. So, I'm just confused as to why it is right is favored over left.




I'm right handed, but I fly with my left hand. What does that mean?!

[avandonk]

It is just a convention so all the signs are in the correct direction.

Real current is the flow of negatively charged electrons yet we still stick to the convention that current flows from positive to negative.


Think about X, Y and Z cartesian coordinate system. This also follows the right hand rule for obvious reasons.

Cross products in vectors also come to mind.

In a mirror Universe the left hand system would be just as valid. Consistency is the only consideration.


Clockwise derives its direction from sundials in the northern hemisphere.

In the southern hemisphere sundials run anticlockwise.

Bert

[mithrandir (Andrew)]

Originally Posted by avandonk

Clockwise derives its direction from sundials in the northern hemisphere.

In the southern hemisphere sundials run anticlockwise.

In the northern hemisphere winds around high and low pressure systems follow a right hand rule. In the southern a left hand rule.

Make a fist using the appropriate hand with thumb out.

Low pressure means rising air. Point the thumb up.
High pressure means descending air. Point the thumb down.

Winds will rotate in the direction of the fingers.

Of course left, right, up and down are all just conventions too.

[Nesti (Mark)]

Originally Posted by avandonk

In a mirror Universe the left hand system would be just as valid. Consistency is the only consideration.

This statement you made Bert I think highlights my point.

I guess it's like flipping all charges in the universe; so long as they are all reversed with equal value - your statement "consistency is the only consideration" - at the same time, there should be no change in the overall structure of the universe; it's conventions are simply flipped.

But I'm still left with the same issue in my mind; why are the "conventions" the way they are...probably too big-a-question to answer.

To me, sundials and wind directions are all perfectly explainable in the context of earth's rotation with respect to a northern aspect versus a southern aspect (Sundials), and movement with respects to mass distribution (coriolis)...these are not a mystery. Even the idea that matter succeeded anti-matter has some logical behavior...but a 50/50 coin toss of a right handed universe over a left handed universe gets me.

The simple notion that the universe (at least some of it's properties) could have been different, without conflict, presents some deeper questioning.

Cheers

[avandonk]

I should have said mirror convention universe. Left or right handed is arbitrary. The conventions have to be a mirror image to still be consistent. Vector algebra makes this more clear.

bert

[erick (Eric)]

For some unknown reason, life on earth has based itself on amino acids that are (nearly) all "L" stereoisomers - sort of a left (or right) handedness in chemical structure. Why? Don't really know.

[gary]

Originally Posted by Nesti

But I'm still left with the same issue in my mind; why are the "conventions" the way they are...probably too big-a-question to answer.

To me, sundials and wind directions are all perfectly explainable in the context of earth's rotation with respect to a northern aspect versus a southern aspect (Sundials), and movement with respects to mass distribution (coriolis)...these are not a mystery. Even the idea that matter succeeded anti-matter has some logical behavior...but a 50/50 coin toss of a right handed universe over a left handed universe gets me.

The simple notion that the universe (at least some of it's properties) could have been different, without conflict, presents some deeper questioning.

Cheers

I think you will find that, indeed, it is "too big a question to answer" today with
any certainty based on current knowledge and will probably be linked to the
formation of the universe during the very early stages of the Big Bang itself.

As you allude to, it is possibly related to aspects of the Big Bang epoch
such as matter-antimatter asymmetry that took the Universe, that we know and
love today, in one "direction" rather than the other. Much has been theorized and
written about why this may have been and quantum fluctuations during the
inflationary period may be at the heart of it.

This field of physics is evolving so rapidly that perhaps someone who tries to
keep abreast of the literature may have a better response to the one I have
just provided above.

[supernova1965 (Warren)]

Could it be that the majority of people who view these phonema are right handed which influences their preceptions.

[sjastro]

Originally Posted by avandonk

In a mirror Universe the left hand system would be just as valid. Consistency is the only consideration.

Parity (spatial coordinate flipping) is conserved for gravity, electromagnetic and strong forces. Not so with the weak force.

A mirror Universe would be a very strange place, if it was able to exist.

Regards

Steven

[Nesti (Mark)]

Originally Posted by sjastro

Parity (spatial coordinate flipping) is conserved for gravity, electromagnetic and strong forces. Not so with the weak force.

A mirror Universe would be a very strange place, if it was able to exist.

Regards

Steven

Spoil-sport!

[circumpolar (Matt)]

Youtube.
Electricity & Magnetism Hand Rules (part one)

http://www.youtube.com/watch?v=9Zy0VHBXxLU&feature=fvw

Just one of many.

[sjastro]

Originally Posted by Nesti

Spoil-sport!

Here is parity explained

http://users.westconnect.com.au/~sja...ial/parity.jpg

[snas (Stuart)]

The right hand rule does not only apply to electromagnetism etc as have been discussed here. It also applies in chemistry and biology. As has already been pointed out here,most people are right handed. DNA is a right handed double alpha helix. Organic molecules such as glucose etc etc can have either right handed or left handed versions. Right handed versions vastly predominate over left. In fact, some organic molecules have vastly different properties between the right and left handed versions to the extent that if the left handed version was the predominant version, the biology of Earth would be quite different.
Stuart

[Nesti (Mark)]

Originally Posted by sjastro

Here is parity explained

http://users.westconnect.com.au/~sjastro/Tutorial/parity.jpg

Geez Steven, that's really cleared it up for me.

"suggest[ing]...that space has a kind of twist"...now that statement pretty much intersects my original question...space having some sort of disposition or tendency for right handedness.

Reason?

Well, without trying to come-off too Mung-Bean, let me point out that ancient energy therapies - don't roll ya eyes just yet people - have EXACTLY the same right hand convention for building and purging Meridians channels (as in Acupuncture, Acupressure etc)...and ALL modalities are the same, no matter their origin (Egyptian to Mayan). 50/50 chance of being right or left maybe, but throughout so many modalities spanning the planet and thousands of years? Surely one must have been left handed?...It doesn't seem so!

So, we see right handed conventions in two totally separate systems of thought and belief, not just different disciplines in science. One known for a couple of hundred years, the other known for several (4 to 5) thousand years.

I'm not saying anything's connected, just pointing out a simple well know fact.

[Jarvamundo (Alex)]

space having some sort of disposition or tendency for right handedness.

ohhh "space" having a twist... this will get interesting... gravity-only is going to struggle here...

Should have a squiz at Bryan Gaenslers (USYD Astronomer Prof.) Magnetic Universe work... interesting stuff.